Recent years have seen technical advances on elucidating genetic information. In the medical field, analyzing disease-relating gene can provide a cure for a disease at a molecule level. Gene diagnosis enables patients to have medical treatment suitable for an individual case. Similarly, using genetic information, pharmacists identify a protein molecule of antibodies and hormones to produce medicines. Even in the agricultural field or food industries, many products benefit from the gene information.
In the techniques handling gene information, scientists put emphasis on the polymerase chain reaction method. With the polymerase chain reaction method, a certain portion of a gene can be amplified in large quantity. Not only for research and development in the molecular biology, the method is widely used in various fields, such as medical microbiology, a clinical diagnosis of hereditary diseases or forensic medicine. Particularly, in the field of the clinical gene diagnosis, it is desirable to be able to analyze the specimens as many as, and as quick as possible. That is, the process of the polymerase chain reaction should be accelerated with a smaller quantity of specimens.
A polymerase chain reaction method is disclosed in Japanese Patent Non-examined Publication No. S62-281. The polymerase chain reaction method is formed of the following three steps of: i) thermal denaturation, ii) annealing, and iii) extension reaction. The cycle of the three steps is repeatedly carried out 30 to 35 times. Firstly, in the thermal denaturation step, the double helix of DNA is separated into individual strands. Next, in the annealing step, a primer is bonded with the strand. Then, in the extension reaction step, polymerase catalyses the replication of DNA. These steps have each necessary condition. Especially, in the annealing step, the temperature depends on the Tm value of a primer to be used. They are usually carried out under 94° C. for 1 min. for the thermal denaturation step; 50 to 60° C. for 1 min. for the annealing step; and 72° C. for 1-5 min. for the extension reaction step.
To complete the polymerase chain reaction, as described above, a temperature-shift with a variation of approx. 40° C. has to be repeated over 30 times. According to a conventional equipment for the polymerase chain reaction, feeding a sample solution into a polypropylene tube (hereinafter referred to as a tube) and then controlling the temperature of the solution in the tube by using an aluminum block (hereinafter, a block). This requires over hours to complete the polymerase chain reaction, mainly because of taking time to shift the temperature of the sample solution to a proper temperature. It takes much time to shift the temperature of the block, and then to transmit the temperature of the block to the sample solution through the tube.
The sample-consuming tube is another problem—due to difficulty of making the tube small, a sample solution with an amount of 10 to 100 micro liters is needed per tube. Clinical treatment requires a gene diagnosis, awaiting an improved structure with which the polymerase chain reaction can be completed in a shorter time with less amount of the sample solution.